Variation among Virginia market-type peanut (Arachis hypogaea) genotypes in susceptibility to tomato spotted wilt virus vectored by thrips (Thysanopetera: Thripidae)

by 1982- Riniker, Steven Douglas

RINIKER, STEVEN DOUGLAS. Variation Among Virginia Market-Type Peanut (Arachis hypogaea) Genotypes in Susceptibility to Tomato spotted wilt virus Vectored by Thrips (Thysanoptera: Thripidae). (Under the direction of Rick L. Brandenburg). Tomato spotted wilt virus (TSWV), a thrips-vectored tospovirus is one of North Carolina’s most important pathogens of peanut (Arachis hypogaea L.). Development of resistant cultivars remains one of the most promising methods to manage the disease. Thirty-two genotypes of virgina market-type peanut were monitored in field tests for TSWV incidence and severity during 2004 and 2005. Cultivar Gregory had a higher density of adult thrips than all other genotypes; breeding lines N01057 and N03054E had the least. Line N03036EJ had the greatest TSWV incidence but did not differ significantly from cultivars Gregory or Perry. Line N00033 had the least TSWV incidence and differed significantly from both Gregory and Perry. The occurrence of late-season chlorosis or peanut yellowing death (PYD) in North Carolina was confirmed to be highly associated with TSWV infection. Breeding line N02051ol (9) had the greatest incidence of PYD, but did not differ significantly from cultivars Gregory or Perry. Lines N03023EF and N01083 had the least PYD incidence and differed significantly from cultivars Gregory and Perry. Plants infected with TSWV but asymptomatic were found in greater abundance than TSWV-infected with symptoms for many of the genotypes. Line N03036EJ had the greatest proportion of infected but asymptomatic plants, having significantly more asymptomatic plants infected with TSWV than Gregory. Line N03054E had the least number of infected but asymptomatic plants, having significantly less asymptomatic plants infected with TSWV than Perry. Cultivar NC-V 11 had significantly more thrips feeding injury and greater density of adult thrips than Perry. No correlation was found between thrips feeding damage or population densities and TSWV incidence, PYD incidence, or the number of TSWVinfected but asymptomatic plants. No significant differences were detected among genotypes for thrips damage ratings or virus severity ratings.